The disclosure relates to an image pickup unit suitable for X-ray radiography, for example, and an image pickup display system using such an image pickup unit.
In recent years, an image pickup unit, which obtains an image based on a radiation ray as an electric signal without intervention of a radiographic film, has been developed for X-ray image-pickup units in medical applications, nondestructive inspection uses, etc. In such an image pickup unit, a photoelectric conversion device and a field effect thin-film transistor (TFT) are disposed for each pixel. Signal charge stored in the pixel is extracted using a pixel circuit including the transistor, and thereby an electric signal based on the amount of radiation is obtained.
As the photoelectric conversion device used for such an image pickup unit, a Positive Intrinsic Negative (PIN) photodiode, for example, may be used. The PIN photodiode has a structure in which a so-called i-type semiconductor layer (an intrinsic semiconductor layer) is interposed between a p-type semiconductor layer and an n-type semiconductor layer. This PIN photodiode is capable of extracting signal charge in an amount corresponding to a quantity of incident light (see, for instance, Japanese Unexamined Patent Application Publication Nos. 2008-277710 and 2011-14752).